IGEVET, CCT LA PLATA CONICET, FCV, UNLP. La Plata B1900AVW, CC 296, Argentina.
Gene. 2013 Apr 25;519(1):150-8. doi: 10.1016/j.gene.2013.01.002. Epub 2013 Jan 16.
In cattle, bovine leukocyte antigens (BoLAs) have been extensively used as markers for diseases and immunological traits. However, none of the highly adapted Latin American Creole breeds have been characterized for BoLA gene polymorphism by high resolution typing methods. In this work, we sequenced exon 2 of the BoLA class II DRB3 gene from 179 cattle (113 Bolivian Yacumeño cattle and 66 Colombian Hartón del Valle cattle breeds) using a polymerase chain reaction sequence-based typing (PCR-SBT) method. We identified 36 previously reported alleles and three novel alleles. Thirty-five (32 reported and three new) and 24 alleles (22 reported and two new) were detected in Yacumeño and Hartón del Valle breeds, respectively. Interestingly, Latin American Creole cattle showed a high degree of gene diversity despite their small population sizes, and 10 alleles including three new alleles were found only in these two Creole breeds. We next compared the degree of genetic variability at the population and sequence levels and the genetic distance in the two breeds with those previously reported in five other breeds: Holstein, Japanese Shorthorn, Japanese Black, Jersey, and Hanwoo. Both Creole breeds presented gene diversity higher than 0.90, a nucleotide diversity higher than 0.07, and mean number of pairwise differences higher than 19, indicating that Creole cattle had similar genetic diversity at BoLA-DRB3 to the other breeds. A neutrality test showed that the high degree of genetic variability may be maintained by balancing selection. The FST index and the exact G test showed significant differences across all cattle populations (FST=0.0478; p<0.001). Results from the principal components analysis and the phylogenetic tree showed that Yacumeño and Hartón del Valle breeds were closely related to each other. Collectively, our results suggest that the high level of genetic diversity could be explained by the multiple origins of the Creole germplasm (European, African and Indicus), and this diversity might be maintained by balancing selection.
在牛中，牛白细胞抗原（BoLAs）已被广泛用作疾病和免疫特性的标记物。然而，尚无任何高度适应的拉丁美洲克里奥尔语品种通过高分辨率分型方法对 BoLA 基因多态性进行了特征描述。在这项工作中，我们使用聚合酶链反应序列基定型（PCR-SBT）方法对 179 头牛（113 头玻利维亚雅库梅诺牛和 66 头哥伦比亚哈顿德尔瓦莱牛品种）的 BoLA 类 II DRB3 基因的外显子 2 进行了测序。我们鉴定了 36 个先前报道的等位基因和 3 个新的等位基因。在雅库梅诺和哈顿德尔瓦莱品种中分别检测到 35 个（32 个报道和 3 个新）和 24 个等位基因（22 个报道和 2 个新）。有趣的是，尽管拉丁美洲克里奥尔语牛的种群规模较小，但它们表现出高度的基因多样性，并且仅在这两个克里奥尔语品种中发现了 10 个等位基因，包括 3 个新的等位基因。接下来，我们比较了两个品种在群体和序列水平上的遗传变异程度以及遗传距离与先前在另外五个品种（荷斯坦、日本短角牛、日本黑牛、泽西牛和韩牛）中报道的遗传距离。两个克里奥尔语品种的基因多样性均高于 0.90，核苷酸多样性均高于 0.07，平均成对差异数均高于 19，表明克里奥尔语牛的 BoLA-DRB3 基因多样性与其他品种相似。中性检验表明，高度的遗传变异性可能是由平衡选择维持的。FST 指数和确切的 G 检验表明，所有牛群之间存在显著差异（FST=0.0478；p<0.001）。主成分分析和系统发育树的结果表明，雅库梅诺和哈顿德尔瓦莱品种彼此密切相关。总的来说，我们的结果表明，高水平的遗传多样性可以用克里奥尔种质（欧洲、非洲和印度）的多起源来解释，这种多样性可能是由平衡选择维持的。
